<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>面试题</title>
  </head>
  <body>
    <script>
      /**
       * 测试题1：先执行变量提升，再执行函数提升
       */

      function a() {}
      var a;
      console.log(typeof a);

      /*
        测试题2:
      */
      if (!(b in window)) {
        var b = 1;
      }
      console.log(b);

      /* 
        测试题3：
     */

      var c = 1;
      function c(c) {
        console.log(c);
      }
      //   c(2);
      console.log(c);
    </script>
  </body>
</html>
